We study the thermodynamic phases of a gas of spin-1/2 atoms in the Hartree-Fock approximation. Our main result is that, for repulsive or weakly-attractive inter-component interaction strength, the superfluid and ferromagnetic phase transitions occur at the same temperature. For strongly-attractive inter-component interaction strength, however, the ferromagnetic phase transition occurs at a hig...

We consider the Hartree-Fock approximation of Quantum Electrodynamics, with the exchange term neglected. We prove that the probability of static electron-positron pair creation for the Dirac vacuum polarized by an external field of strength Z behaves as 1 − exp(−κZ2/3) for Z large enough. Our method involves two steps. First we estimate the vacuum expectation of general quasi-free states in ter...

We studied the linear sigma model withO(N) symmetry at nonzero temperature in the framework of the CornwallJackiw-Tomboulis formalism [1, 2]. Extending the set of two-particle irreducible diagrams by adding sunset diagrams to the usual Hartree-Fock contributions, we derived a new approximation scheme which extends the standard Hartree-Fock approximation by the inclusion of nonzero decay widths....

We describe the new version (v1.75r) of the code hfodd which solves the nuclear Skyrme-Hartree-Fock problem by using the Cartesian deformed harmonic-oscillator basis. Three minor errors that went undetected in the previous version have been corrected. The new version contains an interface to the LAPACK subroutine zhpev. Several methods of terminating the Hartree-Fock iteration procedure, and an...

A new class of analytic wave functions is derived for two dimensional N-electron (2<N,`) systems in high magnetic fields. These functions are constructed through breaking ~at the Hartree-Fock level! and subsequent restoration ~via post-Hartree-Fock methods! of the circular symmetry. They are suitable for describing long-range Coulomb correlations, while the Laughlin and composite-fermion functi...

High-precision Hylleraas-configuration-interaction Hy-CI method variational calculations are reported for the 2 S ground state of neutral lithium. The nonrelativistic energy is calculated to be −7.478 060 323 451 9 hartree, demonstrating that the Hy-CI technique is capable of sub-nanohartree accuracy for three-electron systems. A Hylleraas expansion without linked products of odd powers of rij ...

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A new method is developed to combine the large-basis shell-model and Hartree-Fock methods. The HartreeFock method is used to obtain the absolute uncorrelated binding energies, a starting set of single-particle energies, and the single-particle radial wave functions. The shell model Hamiltonian is modified to remove the monopole terms and these are replaced by Hartree-Fock single-particle energi...

Full three dimensional static and dynamic mean field calculations using collocation basis splines with a Skyrme type Hamiltonian are described. This program is developed to address the difficult theoretical challenges offered by exotic nuclei. Ground state and deformation properties are calculated using static HartreeFock, Hartree-Fock+BCS and constrained Hartree-Fock models. Collective propert...